1. Field of the Disclosure
The present disclosure relates to stereoscopic image processing, and in particular relates to a system and method thereof to obtain a stereoscopic image by analyzing a depth map.
2. Description of the Related Art
As technologies develop, multimedia systems have become more mature, while user demand for higher visual effects have also increased, such as the upgrade of conventional two-dimensional images to three-dimensional images. Different from the two-dimensional images provided by flat displays such as common TVs, the human brain processes the vision of objects with forward/backward depth perception. Depth perception is caused by the distance (i.e. offset) between the left eye and the right eye, and therefore there are slight differences of the images observed by the left eye and the right eye, respectively. The differences of the left eye image and the right eye image are processed by the human brain, thereby generating depth perception. There are three object position levels perceived by the human brain which are a far, middle and near position. Human vision may automatically adjust to a best viewing angle according to the depth of objects. When an object is observed by the left eye and the right eye from different viewing angles, parallax is generated. There are three conditions of parallax according to objects placed at far, middle and near distances, wherein the three conditions are (1) positive parallax, (2) zero parallax, and (3) negative parallax. The positive parallax is illustrated in FIG. 1A. The left eye image and the right eye image are placed at the position L and R of the screen 101 respectively, wherein the position L is the intersection point between the sight line of the left eye and the screen 101, and the position R is the intersection point between the sight line of the right eye and the screen 101. The sight lines of the left eye and the right eye are crossed behind the screen 101, and the stereoscopic image is displayed at the cross point behind the screen 101. The zero parallax is illustrated in FIG. 1B. The left eye image and the right eye image are overlapped exactly on the screen 101, and the image is also displayed on the screen 101 without stereoscopic perception. The negative parallax is illustrated in FIG. 1C. The left eye image and the right eye image are overlapped completely at the position L and R of the screen 101. The sight lines of the left eye and the right eye are crossed in front of the screen 101, and the stereoscopic image is displayed at the cross point in front of the screen 101.
Although a stereoscopic image can be captured by a stereoscopic camera or a stereoscopic video camera, these devices are not popular and are expensive, and thus not easily attainable. Therefore, algorithms for converting existing two-dimensional images or films into stereoscopic images have been developed. Depth information is usually used in stereoscopic image algorithms, wherein the depth information can be expressed by a depth map. The generation of the depth map can be achieved by using a depth camera, a stereoscopic video camera, or corresponding stereoscopic imaging algorithms. A well-known depth map expresses various depths of different objects in the picture by using a gray-level image, such as gray levels 0-255, wherein the gray level 0 indicates that the object is located at the farthest position from the lens, and the gray level 255 indicates that the object is located at the nearest position from the lens.
Conventional stereoscopic image algorithms, which obtain the left eye/right eye images by using the depth map of the two-dimensional image, may perform a pixel shifting process at different offset levels to the original two-dimensional image objects, but the differences of the objects viewed by the left eye and the right eye are ignored.